Katy Perry got in on the weekly social media fun posting an adorable old childhood photo with her sister Angela Hudson, which will be the cover for her upbeat new single "Birthday."

"In honor of #TBT may I present the cover of my NEXXXT single," she wrote on Twitter. In the pic, the young "Dark Horse" singer and her sis rock rather large bows in their hair and similar floral dresses.

Hunger Games actress Elizabeth Banks took to Instagram to share a risqué shot from a few years back. "Sorry to disappoint but I am NOT naked in this #ThrowbackThursday pic from Cannes in 2009. I'm wearing a robe. You just can't tell."

Katherine Heigl also got in on the action, channeling Austin Powers in a snapshot from her Roswell days. "Back about 14 years to the Roswell set, posing with the younger 'mini-me' versions of our characters. #TBT," she captioned the photo.

CeeLo Green also took us back in time with a vintage shirtless pic. "#TBT School days at Riverside Academy," he wrote.

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